Drugstore beetle
Stegobium paniceum (Linnaeus)

Order: Coleoptera
Family: Anobiidae
Acronym: SPA

Ecology

The drugstore beetle is distributed worldwide, but it is found more often in temperate climates. In temperate climates, it can survive winter in unheated conditions. It feeds on a wide range of dried commodities that are of animal or vegetable origin including grain and cereal products. It is similar in appearance to the cigarette beetle.

Damage

The drugstore beetle consumes a wide range of foods that includes spices, chocolate, seeds, flour, leather, feather pillows and dog food. Despite its wide range of food, it prefers vegetable-matter that is rich in starch.

The larva causes the most damage because it feeds on the commodity. It also burrows into the commodity to construct its cocoon. This leaves irregular holes.

The adult does not feed on the commodity, but it does chew holes in the commodity’s packaging when it emerges. This leaves a large, neat hole.

A sign of infestation is that the product becomes contaminated with larval cocoons, frass and dead adult beetles.

Life history

The adult is oval-shaped. It is 2 to 3.5 mm long and is reddish brown. It can be distinguished from the cigarette beetle by its antennae with a 3-segemented club and its striated elytra. The elytra are covered in fine hairs. The adult flies at night. It has a short life span: males live for 18 days and females live for 30 days.

Breeding conditions are temperatures between 15 and 34°C, and relative humidity at 35%. The female lays 100 eggs over its 25-day lifespan. It lays eggs singly in crevices within the commodity.

The larva is white and covered in numerous long hairs. It becomes crescent-shaped and immobile as it matures. It is 3 to 4 mm long. The larva can develop in 40 days with optimal conditions of a 30°C temperature and a relative humidity between 60 and 90%. The larva pupates in a cocoon that is constructed with particles of food. The entire life cycle may take 5 to 6 weeks to complete.

Control

Controlling insect infestations

Images

Drawing of an adult drugstore beetle.

Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org
Adult drugstore beetle

Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org
Adult drugstore beetle - side view